public class GuiTest extends PaginableInventory {

    private final Player player;

    public GuiTest(int sizeGui, Player player) {
        super(sizeGui); //9
        this.player = player;
    }

    private List<Icon> iconsMaker() {
        List<Icon> icons = new ArrayList<>();

        for(int i = 0; i == 27; i++) {
            Bukkit.broadcastMessage(String.valueOf(i));
            icons.add(new Icon(new ItemStack(Material.BEDROCK), a -> {}));
        }

        return icons;
    }

    @Override
    protected void registerItems(Player player) {
        setIconsPage(iconsMaker());
        setPage(0);
    }

}